Author Topic: Engine mount studs sheared - advice on fix pse! (Read 18040 times)

jameshoward · « **on:** January 24, 2008, 13:08:55 »

I have known for a while that 2 of the studs on the engine block to which the engine mount arm attaches are 'missing' presumed sheared off, see the 3 photos below.

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The studs have not been present since I got the car. I now want to sort this out as I fear damage will result if I don't fix it.

I assume they are studs that are affixed to the block somehow. Do they screw in, or are they welded to the block? I am not certain whether there are 2 studs sheared off inside the block. If so, do I have to remove the engine to get this sorted?

Basically, I have no idea where to start and have never had the engine out of the car. Has anyone experienced this before, and can anyone tell me what right looks like, what I am potentially dealing with and whether I need to remove the engine to rectify the problem.

Just for fun, and just as long as you can provide some useful advice, here are 2 photos that have nothing to do with my current problem. (But you can only look at it if you can help me out!)

Thanks,

James

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Paddy_Crow · « **Reply #1 on:** January 24, 2008, 15:30:56 »

It looks to me like the stud is sheared off at the surface of the mount arm casting. I would be willing to bet they are threaded into the block, wielding a steel fastener to a cast iron block would be costlier than just drilling and tapping the block.

I have not done this job, but I would think it can be done without pulling the engine. You will need to support the engine to remove the arm, just like if you were replacing the rubber mounts. The question I can't answer is how much room there is to work on it. Also, removing the broken stud can be a problem if it's rusted in.

Democracy is two wolves and a lamb voting on what to have for lunch...

jeffc280sl · « **Reply #2 on:** January 24, 2008, 16:59:39 »

Now that's something you don't see in a garage everyday. What is the mpg on your tank?

According to the EPC the stud is part number N000939010011 and from the picture of the part it appears to be threaded on both ends. You may get very lucky when you support the engine and remove the arm. The stud may back out with a pair of vice grips. I hope so!

Jeff C.
1970 280SL 4-speed

psmith · « **Reply #3 on:** January 24, 2008, 17:55:33 »

Isn't this a job for an "easy out"? Although in my experience, they're not exactly "easy" If the hole isn't drilled straight down the center of the stud, the easy out can break off itself! [

!]

Pete S.

ja17 · « **Reply #4 on:** January 24, 2008, 20:12:27 »

Hello James,

The stud is just threaded into the block. I have seen these studs back out with the nut many times. This may be the case. Check to make sure that the hole is not empty first. Then we can go into some fixes.

Joe Alexander
Blacklick, Ohio

Paddy_Crow · « **Reply #5 on:** January 24, 2008, 20:32:43 »

It's hard to tell for sure, but the stud looks to me like it twisted off which means it's probably frozen. If that's the case, I don't see an EZ Out removing it.

Democracy is two wolves and a lamb voting on what to have for lunch...

Shvegel · « **Reply #6 on:** January 25, 2008, 08:28:50 »

I would be willing to bet the studs just fell out. the top of the mounts are under compression so I don't think the studs would snap unless the nuts were grossly overtightened.

Regardless I wouldn't worry too much since again the upper studs are not loaded too heavily. I would think they would be okay until you pulled the engine and drilled them out.

Having been a mechanic for some 25 years now I have come to hate easy-out type devices unless the bolt has snapped due to overtightening and has not bottomed in the hole. Since the studs were probably set into the block before the mounts were installed I would guess it would be fruitless.

It seems like everytime I have used one I have ended up snapping it off in the bolt which leaves you with a hardened steel plug where you know need to drill again...not fun.

All that being said the best Screw Extractors are made by Ridgid tool(also branded "Blue Point" for Snap-on) and involve specially sized drill bits and small fluted rods which you drive into the hole you drilled. A "nut" is slipped over the rod and you can turn the stud out.

I like these because they don't rely on a cone shape which I think tends to expand the very remnant you are trying to extract.

Ridgid set #10 Or Snap-On #1020

merrill · « **Reply #7 on:** January 25, 2008, 12:08:45 »

any engine rebuilder or maybe even MB can sell you new studs.

Just getting to the old ones is not gonig to be fun, getting them out (if they are still there) probably will be more fun.

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

jameshoward · « **Reply #8 on:** January 26, 2008, 11:09:14 »

Thanks for the replies to date. I checked the holes today and can confirm, annoyingly, that the studs are sheared off inside the block, not just inside the arm mount.

So, to that end, I suppose I need to drill them out and put new ones it. I take your point Shvegel about just leaving it, but I have time at the moment and would like to get it done.

I guess this sends me down the route of using a stud extractor set.

I also need to replace the rear engine (transmission) mount. So, any recommendations on whether it's best to do the engine mount thing with the engine in the car? I've never removed the engine in the year or so I've had the car - I admit to being somewhat intimidated by that level of tinkering - but perhaps it is the way forward. I've read up on the Haynes manual way of removing transmission and engine together; what's the job like and more importantly are there any major pitfalls that would tip me away from removing the studs that way? Or am I better off stuggling through leaving the engine in place?

Grateful for any advice now that I know the scope of the problem.

And Jeff, to answer your question about tanks and MPG, it doesn't really equate to cars. We don't tend to sit around in our cars with the engines running waiting for stuff to happen. Tanks do and tend to leave one or both of their engines running (there is a main engine which on that tank is a 36 litre Rolls Royce CV12 producing up to 1500bhp and an auxilary generator of about 2.0l which is bascially a diesel car engine; it's there to provide power when the main engine is off but is pretty much needed when the main engine is on because of the increased power requirements). As a result, we tend to work on a series of mean calculations based on something called a 'battlefield day' which includes driving cross country, on tracks/roads, and just hanging around waiting to shoot something. The MPG figure - using the track mileage of a battlefield day divided between the fuel consumption - would put the MPG between 7-9 gallons to the mile. (Proper gallons, that is: good old fashioned Imperial ones!) In other words, they use a lot of diesel. Thanks for the part numbers.

James

Paddy_Crow · « **Reply #9 on:** January 26, 2008, 11:27:49 »

Removing an engine is a major job. I wouldn't recommend doing it unless absolutely necessary, and only someone experienced with that type of work should undertake it. Again, I have not done the job on a 113, but replacing motor mounts is a relatively routine job on most cars. With a well placed piece of 2X4 and a hydraulic floor jack, supporting the engine while replacing the mounts one at a time isn't difficult.

As for extracting the broken stud, good luck with it. I have yet to find a good way of doing it without damaging the threads. It takes a lot of patience, usually involves nibbling away at it. Sounds like someone overtightened it once upon a time and decided to just leave it.

If it were my car, I would be tempted to just leave the sleeping dog be...

Democracy is two wolves and a lamb voting on what to have for lunch...

Shvegel · « **Reply #10 on:** January 27, 2008, 04:49:23 »

James,
Sorry to hear they are still in there. My only word of caution is to avoid drilling through the side of the block.

I would suggest removing one of the other studs and measuring the depth of the hole in the block and make a mark or stop on the drill bit.

A good friend was drilling through a plug on the side of the block of a new Volvo so he could install a block heater. He managed to drill right through the plug, the block and the side of the piston.

al_lieffring · « **Reply #11 on:** January 28, 2008, 08:13:51 »

The best way that I have found to get a stud broken off flush in an engine block is to place a nut of the next size larger over the stud and then with a MIG welder weld weld down through the center of the nut to the top of the stud untill the hole is completly filled in.

The heat from the welding will loosten up the stud from the block, when still hot put an socket on the nut and the stud will turn with the nut. if it breakes off just weld another nut on, repeat untill the stud spins out freely.

Even if the stud is broken off below the surface of the block the MIG weld will not stick to the iron block, just to the steel stud. This method works on aluminum castings too.

The location of these studs would make it difficult to get in with a welder though,

Al Lieffring
66 230SL

psmith · « **Reply #12 on:** January 28, 2008, 21:50:29 »

Thanks Al, that's a great tip. It's always nice to have options when trying to solve a difficult problem.

Pete S.

Mike Hughes · « **Reply #13 on:** January 29, 2008, 11:16:27 »

quote:
Originally posted by Shvegel

James,
A good friend was drilling through a plug on the side of the block of a new Volvo so he could install a block heater. He managed to drill right through the plug, the block and the side of the piston.

Instant two-stroke!

- Mike Hughes -ô¿ô-
1966 230SL Auto P/S
Havanna Brown (408)
Light Beige (181)
Cream M-B Tex (121)

graphic66 · « **Reply #14 on:** January 29, 2008, 11:32:22 »

I agree with AL, I have extracted many broken bolts with my mig welder. Another tool that has worked great for me is my left handed drill bits that came with a set of completely worthless easy outs. The left handed bits usually, when drilling just back the broken bolt right out with the heat of drilling and the torque of the bit. The easy outs have, as previously stated caused me more problems than help. If you see a set of left handed drill bits they are well worth adding to your tool kit. And the mig welder is an amazing tool, only second to my Oxy-Acytelene torches in handiness. The Mig has made a metal burner like me into an OK welder.

psmith · « **Reply #15 on:** January 29, 2008, 13:27:29 »

Another good tip! Thanks

Pete S.

jameshoward · « **Reply #16 on:** January 29, 2008, 14:37:50 »

Thanks for the replies.

Although I ahve access to a MIG welder, I think I will try a little head and a left hand drill bit as per Graphic66's reply. I've been checking on the internet and can only find imperial sets.

Would I be correct in thinking that the size of the drill isn't vital, rather it's the process of using it together with crossing ones' fingers that the stud will come out that is important? If that's the case, I'll just buy an imperial set. However, can anyone tell me the actualy size of the stud and how far it might screw into the block so I can avoid the instant 2 stroke conversion mentioned by Mike?

Would putting some heat from a blow torch help before I drill?? (I haven't even looked to see if I can fit a drill in that space come to that - I'll let you know).

James

graphic66 · « **Reply #17 on:** January 29, 2008, 15:19:38 »

The size of the bit is not really important. It is best to start with a small bit and keep going larger. Getting started in the center and straight is important. Sometimes I have ended up a little off center and you can, using a punch or small chisel cave in the stud and get it out like that. I have also used a hack saw blade ground down a little thinner to fit in your drilled hole to cut the stud to the threads and sectioned it out. Heat can always help, drilling will cause some heat. Use a good amount of oil when drilling, I like a cutting oil for drilling but any oil will help. That will help to keep your bit sharp and keep it from binding and breaking off. Also when chucking your bit tighten your chuck using all 3 arbors on the chuck, not just one as this will get your bit tighter in your chuck. Keep oil away from the chuck as this can loosen the chuck on you. Also and importantly, before starting to drill get a punch and really beat the end of the stud, this can really help loosen things up. Then find the center and punch it and be very carefull to start centered. I have also cut slots in the end if possible and used my hand held impact driver with a screwdriver bit with some success.

psmith · « **Reply #18 on:** January 29, 2008, 18:39:23 »

This might be a dumb question, but doesn't the mount have a smooth bore where the stud goes through, like a cylinder head? It doesn't make sense that it would be threaded, so you should be able to remove the other nuts and slide the mount off the frozen stud exposing a little bit of the stud to grab on to.

Pete S.

jameshoward · « **Reply #19 on:** January 30, 2008, 04:37:13 »

Pete,

I see what you mean and I live in hope. However, I have scientifically poken a piece of wire into the mount and found that the stud appears to be sheared off just inside the block. Which is all a bit dull. I do hope there will be something to grab on to. Worse, I suspect that the studs were broken off by the complete jackass of a mechanic who I got to weld in the new floor panels and replace the original rubber mounts back when I was serving overseas and wanted the car ready-ish for when I got back. Hence I now try to do as much as I can on my own without leaving some utter moron to bugger up more things and not tell me about it. (rage ends).

James

glennard · « **Reply #20 on:** January 30, 2008, 08:52:50 »

Usually the studs in the block have oil from leaks, spillage, etc. and come out easily-relatively. Support motor, take the other 3 nuts off, remove bolt at end of motor mount support, remove motor mount, see how much stud is there, squirt PB Blaster, report back----

jameshoward · « **Reply #21 on:** January 30, 2008, 11:34:25 »

Roger that.

Moderator: "Roger that" = "I understand"

Shvegel · « **Reply #22 on:** February 01, 2008, 08:29:30 »

James,
Another nice feature of the Ridgid/Snap-on screw extractors is that they come with drilling bushings. If you have access to a right angle drill you could slip one of the bushings in the hole in the mount then drill at least part way through the stud which would give you a hole right down the center. Then you could pull the mount and finish the job.

jameshoward · « **Reply #23 on:** March 02, 2008, 14:55:37 »

Evening All,

Thanks for the advice. Based on the musings herein, I have purchased a set of left hand thread drill bits and a right angle drill.

I don't have a parts list, so trusting to Jeff I am going to order 2 x new studs, part no N000939010011 - (has anyone else got anything different for the studs??)

So next weekend, supporting the engine, I will remove the other studs to remove the arm, then attempt to drill out the old ones in the hope that as I drill, they will come out. If they don't, I suppose I'll have to tap and rethread, etc. Boring. Not least because I don't have the stuff to do all of that.

Any last minute advice would be welcome, as ever.

James

jameshoward · « **Reply #24 on:** March 03, 2008, 12:20:52 »

Now here's a curious thing - the 'active topics' thingymajig that I now use after the splitting up of the forums in order to find out what's new shows jeffc280sl as having made a post after my previous post (!) before I made this one - only there is no post after mine.

Freaky.

Jeff? Are you out there???

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Author Topic: Engine mount studs sheared - advice on fix pse! (Read 18040 times)

Paddy_Crow

jeffc280sl

psmith

Paddy_Crow

Paddy_Crow

al_lieffring

psmith

graphic66

psmith

graphic66

psmith

glennard